Process Design For The Recovery Of 18000t/a Chromium-containing Aluminum Residue

Chromium salt is an important inorganic chemical products.Chromium-containing aluminum residue is a kind of solid waste, which is produced by neutralization aluminum removal from chromium salt production process. Chromium in the chromium-containing aluminum residue in the form of a highly toxic Cr(â…£) must be removed,which easily lead to the occurrence of environmental pollution problems. Chromium-containing aluminum residue also exists large amounts of aluminum, which must be recycled. As a consequence, removing Cr(â…£) and recycling aluminum from chromium-containing aluminum residue not only can solve environmental pollution problems, but also can bring considerable economic benefits.Electrodialysis technology is applied to chromium removal of aluminum residue in the process design. Hexavalent chromium salt in the form of binding states and crystal states can be migrated from thick aluminum residue by the force of electric field, which solves the problem of chromium removal of aluminum residue.In addition, the process can realize the recycling use of raw materials, intermediate products and products, and thus significantly improve the utilization of resources.Detailed design and optimization of the process design was carried out. The production process is divided into three sections, namely, beating and water-washing section, electrodialysis section and NaOH leaching and carbonation decomposition section. Among them, the electrodialysis section is continuous production process, the remaining section is intermittent production process. Beating and water-washing section is two-stage beating and water-washing, which conducts a preliminary chromium removal. Electrodialysis section is three-stage electrodialysis, which conducts an in-depth chromium removal. NaOH leaching and carbonation decomposition section contains two parts of NaOH leaching and carbonation decomposition, which is two-stage NaOH leaching and two-stage carbonation decomposition, so as to achieve the purification of metal aluminum, and the final Al(OH)3 product was prepared.The material balance and heat balance calculation for each device and device were carried out. And the stirring kettle and electrodialysis device were detailed design, centrifuge, pumps, piping and other auxiliary equipment were selected. In addition, the workshop layout, automatic control and instrumentation as well as investment estimates were calculated and designed in this design. And a flow chart diagram(PFD diagram), process piping instrumentation diagram(PID diagram), equipment diagram and plant layout diagram were drawn by Auto CAD and other professional design software.